1. Field of the Invention
This invention relates to a disk-rotating drive mechanism for a floppy disk, and in particular, to a metal drive pin used in such disk-rotating drive mechanism.
2. Description of the Related Art
Disk-rotating drive mechanisms, such as rotation drive mechanisms for 3.5-inch floppy disks, have a shaft engaging the center hole of the disk, a rotating unit that rotates the shaft, a chucking lever and a drive pin attached to one end of the chucking lever. The second end of the chucking lever is supported by the rotating unit. The drive pin engages the drive pin engaging hole positioned eccentrically from the center hole of the disk and drives the rotation of the disk.
The disk-rotating drive mechanism disclosed in Japanese Laid-Open Patent Application No. 5-41011 is one example. In this example, the drive pin and chucking lever are integrated using resin molding. When a disk hub mounting section mounts the disk, the disk is tilted and rides up over the drive pin until the resin-molded drive pin engages the drive pin engaging hole in the disk. In this example, the upper surface of the drive pin is tilted so that the drive pin is relatively flat when the drive pin is not engaging the drive pin engaging hole in the disk and friction with the drive pin is reduced.
In the disk-rotating drive mechanism disclosed in Japanese Laid-Open Patent Application No. 4-38751, the drive pin and the chucking lever are made of different materials. In this example, one end of the chucking lever pivots on the rotating unit, which rotates with the rotating axis. The chucking lever is allowed to rotate parallel to the rotating unit with the drive pin situated on the other end of the chucking lever. The chucking lever is also equipped with a plate spring so that the drive pin moves axially and falls into place when the drive pin is to engage the drive pin engaging hole in the disk. This displacement of the drive pin is restricted to a given range.
In recent years, disk-rotating drive mechanisms have become thinner and faster. As disk-rotating drive mechanisms have become thinner, the space between the rotation drive shaft and the disk hub mounting section above the hub platform on the outside edge of the drive shaft has become smaller. The space between the disk hub mounting section and the upper surface of the drive pin has also become smaller.
When the disk-rotating drive mechanism mounts the disk on the hub platform, the drive shaft engages a square center hole in the center of the disk hub, and the drive pin engages a rectangular drive pin engaging hole positioned eccentrically from the center hole in the disk. Then, the disk is centered and can be rotated by the rotation drive mechanism. However, the drive mechanism begins to operate when the disk has been placed on the hub platform. When the drive shaft engages the center hole in the disk hub, the disk hub is generally positioned over the drive pin and the drive pin engages the drive pin engaging hole in the disk hub when the drive pin is rotated along with the rotating unit and the chucking lever.
Therefore, when the space between the disk hub mounting section and the upper surface of the drive pin is narrowed, and the disk is positioned on the disk hub and the drive pin extends into the drive pin engaging hole on the disk hub to center the disk, the drive pin and the drive pin engaging hole are often incompletely engaged. The drive pin moves out of the drive pin engaging hole when the disk is chucked on the hub platform.
As the speed of disk-rotating drive mechanisms increases, the insertion of the drive pin into the drive pin engaging hole in the disk hub when the disk hub is chucked on the hub platform can cause it to be struck hard by the drive pin. Therefore, resin-molded drive pins cannot withstand the impact. The drive pin is eventually damaged or worn, which reduces the precision of the disk centering process. As a result, the mechanism may become less reliable. A mechanism was disclosed in Japanese Laid-Open Patent Application No. 4-38751 in which the drive pin and the chucking lever are made of different materials. When the drive pin is made of metal, the problem of drive pin damage and wear is solved. However, when a disk is centered and the disk hub is positioned over a metal drive pin, the disk hub can come into contact with the drive pin, causing damage to the disk hub.
A mechanism is disclosed in Japanese Laid-Open Patent Application No. 5-41011 in which the surface of the metal drive pin is inclined. As a result, the disk hub is parallel to the upper surface of the drive pin before the drive pin engages the drive pin engaging hole in the disk. Therefore, the disk hub is less likely to be damaged if the upper surface of the drive pin comes into contact with the disk hub. In this mechanism, the drive pin, peripheral chucking lever, rotating unit and disk mounting section are all manufactured with greater dimensional precision, which makes it even less likely that the upper surface of the drive pin will come into contact with the disk hub. However, the edge of the drive pin can still come into contact with the disk hub in this mechanism. This problem remains unsolved in this reference.
Commonly assigned U.S. Pat. Nos. 5,311,383(""383) and 5,648,881 (""881) describe a chucking mechanism with a plastic drive pin that has at least one planar surface engaging a drive hole of the disk hub when chucking is completed. This drive pin planar surface extends in a plane that is at a non-zero angle to a plane containing a portion of a surface of a rotary member that contacts the disk hub. More particularly, the patents ""383 and ""881 teach that this non-zero angle is 2xc2x0xc2x11.5xc2x0.
Accordingly, the present invention is directed to a disk-rotating drive mechanism that substantially obviates the above-discussed limitations and disadvantages of the related art.
An object of the present invention is to provide a disk-rotating drive mechanism in which the drive pin is made of metal and configured to withstand high speeds and to prevent damage to the disk when the disk is chucked.
Additional features and advantages of the invention will be set forth in the descriptions that follow and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention provides a disk rotating drive mechanism for rotating a floppy disk having a disk hub with a center hole and a drive pin engaging hole positioned eccentrically from the center hole, the disk rotating drive mechanism comprising a rotating shaft for engaging the center hole in the disk hub, a rotating unit that rotates with the rotating shaft, a chucking lever pivotally supported by the rotating unit at one end, and a drive pin made of metal and provided on another end of the chucking lever for engaging the drive pin engaging hole in the disk hub to rotate the disk. The drive pin defines an upper surface that is inclined to be higher at an outside portion farther from the rotation shaft than at an inside portion nearer the rotating shaft. The drive pin further defines a chamfered section formed at the outside edge of the inclined upper surface. Further, the drive pin defines a front surface corresponding to a portion of the drive pin that is leading in a rotation direction of the rotating unit, and a back surface corresponding to a portion of the drive pin that is trailing in the rotation direction of the rotating unit, wherein the front surface is curved and the back surface is flat.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.